1. Field of the Invention
The present invention relates to plunger, and more particularly to a plunger of a syringe.
2. Description of Related Art
A conventional plunger of a syringe in accordance with the prior art shown in FIG. 3 is adapted to be slidably partially received in a barrel of the syringe, and comprises a shaft (1) and a rubber bulb (2) mounted to a first end of the shaft (1).
The shaft (1) includes a second end opposite to the first end thereof and having a thumb rest (101) laterally extending from the second end of the shaft (1). The shaft (1) includes a stopper (102) radially extending from the first end of the shaft (1) and a stub (103) longitudinally extending from the stopper (102). A flange (104) radially extends from a distal end of the stub (103) and a connector (105) centrally longitudinally extends from the distal end of the stub (103). The stub (103) and the connector (105) are tapered and each has a diameter gradually reduced relative to a free end of the connector (105).
The rubber bulb (2) includes a tapered through hole (201) centrally defined therein for receiving the stub (103) and partially receiving the connector (105). An annular groove (202) is defined in the rubber bulb (2) and laterally communicating with the tapered through hole (201) in the rubber bulb (2) for receiving the flange (104) of the plunger. The stopper (102) of the shaft (1) can prevent the first end of the shaft (1) from overly passing through the rubber bulb (2). The rubber bulb (2) abuts against an inner periphery of the barrel (3) to provide an airtight effect between the plunger and the barrel (3) during operating.
However, the conventional plunger of a syringe in accordance with the prior art includes the following disadvantages.
1. The produce rate is low and the cost is expansive when the rubber bulb (2) is mounted to the first end of the shaft (1) by manpower.
2. The rubber bulb (2) may jumps off the shaft (1) during assembling because the diameter of the through hole (201) is smaller than that of the flange (104).
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional plunger of the syringe.